The present invention relates to devices for gasification of carbonaceous materials, and in particular to devices for obtaining significant amounts of combustible gas from the combustion of such materials, in particular wood chunks and wood waste.
Devices for the gasification of wood material are known which in general consist of a gas-tight combustion chamber which is connected to a means for charging the chamber with material to be burned and a means for removing the ash which is formed as a result of the combustion. Such devices generally have a number of nozzles for supplying combustion air to the chamber as well as discharge lines for removing the combustible gases.
Such conventional wood gas generators have a circular cross section and the air which is necessary for the gasification is supplied through a number of nozzles which are disposed about the circumference of the circle. A partial combustion of the wood is thus obtained, whereby oxygen in the combustion air combines with the carbon in the cellulose of the wood. The gas mixture resulting from such combustion generally consists of combustible components such as carbon monoxide (CO), hydrogen (H.sub.2), nitrogen (N.sub.2), hydrocarbons such as methane (CH.sub.4), and non-combustible components such as carbon dioxide (CO.sub.2) and water vapor (H.sub.2). If the gas mixture is mixed with the primary air supply which is used as the combustion gas a partial decomposition of the CO.sub.2 and H.sub.2 O respectively into CO and H.sub.2 occurs if sufficient heat is provided, whereby the liberated oxygen bonds to the remaining carbon of the wood material. By supplying secondary air through the ash, unburned material in the ash can be further converted into gas, to the extent that the material temperature is sufficient in the zone where the secondary air interacts with the ash.
Because of the circular cross section of such conventional wood gas generators, such generators have a relatively small material handling capacity because the penetration depth of the gasification air is limited. If the circular cross section is enlarged, a portion of the cross-sectional surfaces are either minimally or not at all exposed to the primary air supply and the material located in such cross-sectional areas is poorly or not at all gasified.